Clot retrieval could help improve disability outcomes in mild stroke, researcher tells ANZAN


By Natasha Doyle

23 May 2022

A study suggesting clot retrieval may help improve disability outcomes in mild stroke should give neurologists more confidence advocating for the procedure in certain affected patients, an Australian researcher told the ANZAN 2022 meeting.

The retrospective study of 83 mild stroke patients with anterior circulation large vessel occlusion found those who underwent clot retrieval with or without lysis were more likely to have “good” (modified Rankin score [mRS] < 3) or “excellent” (mRS < 2) disability outcomes at 90 days than individuals receiving conservative medical treatment or lysis alone (P < 0.01 and P < 0.02 respectively).

It also saw clot-retrieval patients achieve small, though not statistically significant, symptom improvements by 90 days, where less aggressively-treated patients slightly deteriorated (NIH stroke score [NIHSS] change: -2.52 versus +0.63 in lysis-only recipients and +1.86 in conservatively-treated patients, P = 0.33).

Although not all outcomes reached statistical significance, study author and presenter, Dr Christopher Kwan told the limbic that even numerical changes can reflect “much better subjective day-to-day functioning in [mild-stroke] patients”.

While larger, more definitive, studies are needed, the findings “should make neurologists feel more comfortable about advocating for clot retrieval” in particular patients presenting for mild stroke, he said.

His study assessed patients who presented to Princess Alexandra Hospital’s Stroke Unit within 24 hours of symptom onset, scored less than six on NIHSS, had anterior circulation large vessel occlusion on CT angiography and had very-little pre-stroke disability, with baseline mRS scores less than one.

The latter condition follows current guidelines which don’t recommend clot retrieval in people with some level of disability and dependence on others in day-to-day function, said Dr Kwan, who works in the hospital’s neurology department.

Of his cohort, 30% received clot retrieval with or without lysis, a quarter had lysis alone and the remainder had conservative medical therapy.

Over 90 days, 100%, 82% and 65% of clot-retrieval, lysis-only and conservative patients achieved “good” mRS scores, while 96%, 77% and 63% reached “excellent” scores, respectively.

Adverse events were “extremely rare”, Dr Kwan said, noting one intracranial bleed and one death in the lysis-only group, and two deaths in the conservatively-treated group.

Treatment decsions

Younger patients were more likely to take on aggressive therapy than their older, more comorbid counterparts, however, patient and clinician comfort and procedure feasibility may also influence treatment decisions.

“Anecdotally, here in Brisbane, it can be difficult to get timely clot retrieval when we’re serving a fairly large geography and don’t have as many staff that live close by to be on beck and call, especially when [a case] comes after hours,” Dr Kwan said.

Additionally, “clot retrieval technology is relatively new” and “the bulk of studies have focused on more severe strokes — people with high NIHSS scores, for which there’s absolutely no question, these people, if they qualify, would go for the aggressive treatment”.

As a result, there are “no real guidelines to tell [neurologists] what to do for really mild stroke [patients] who’ve actually got occluded arteries seen on CT scans”.

Therefore, clinicians may be uncomfortable offering the procedure and patients can miss out on timely care.

“There’s a one-in-four chance that people with these so-called ‘mild strokes’ can still progress, miss out on the appropriate time frame to actually proceed with clot retrieval and lysis and subsequently, [their outcomes] may not be so good,” Dr Kwan said.

He noted that ‘mild’ was “a bit of a misnomer” and patients with objectively low NIHSS and mRS scores could still subjectively have “extremely disabling” symptoms.

Larger, prospective studies are needed to confirm the best treatment plan for mild stroke patients, but Dr Kwan hopes the current study will help neurologists feel “more comfortable” offering the clot retrieval to those with similar characteristics to this study, he said.

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